1: With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 1 h; 2: With tri-isopropoxy-borane in tetrahydrofuran; hexane T=-78 - -30°C; 2 h; 3: With hydrogenchloride; water in tetrahydrofuran; hexane

1: 2-bromo-3,4-dimethyl-2-cyclopenten-1-one ethylene ketal With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 1 h; 2: tri-isopropoxy-borane in tetrahydrofuran; hexane T=-78 - -30°C; 2 h; 3: With hydrogenchloride in tetrahydrofuran; hexane; water